Factory chambering Garands

[Grizzly Adams]

Always wondered if factory Garands were built with short chambered barrels and finished the same way we home builders are doing it. Seems like a very inefficient process when you've got to turn these things out by the millions

Grizz

 

[The Wizard]

When produce at the United States government arsenal or at commercial firms under contract with the United States government M1 barrels were "fully" chambered in accordance with the appropriate drawing. The tolerances on the barrel, receiver and bolt were such that when assembled the headspace would be within tolerance. Part of the inspection process was to check headspace. If it was out of tolerance the rifle was reject and sent to "rework".

 

[purple]

All US GI factory barrels were partially chambered and required finish reaming when installed on a receiver with a particular bolt. This short chambering accounted for variations in manufacturing tolerances among bolts and receivers as well as wear on used bolt lugs and lug seats in the receiver. I've installed quite a number of new US GI barrels and all but one required finish reaming to establish proper headspace. The one exception was with a used bolt which had enough wear for the chamber to accept a "go" gauge without any finish reaming. See US Army TM9-1275 for details of finish reaming to establish correct headspace when installing a replacement barrel. M1903 Springfield replacement barrels were short chambered for the same reason.

 

[sunray]

Rifles were shipped ready to be issued. The U.S Army and Marines didn't have the time or trained people to "finish" making a weapon. A barrel by itself is a different thing.
TM-9-1275 is available as a free .pdf download here. Add the W's and note the need for the provided UN & PW.
.biggerhammer.net/manuals/